(1) Field of the Invention
The present invention relates to a collimator for a beam of radiation which allows rapid adjustment of the cross-section of the beam for different patients or other surfaces to be irradiated. In particular, the present invention uses bundles of adjustable clamped rods to shape the cross-section of the beam.
(2) Prior Art
Collimator devices for radiation are well known to the prior art. Most of them provide beams with a fixed cross-section. The problem is that this configuration is cumbersome where the cross-section of the beam has to be changed such as in patient treatment with the radiation in a defined area of the body.
Variable collimator devices are also well known to the prior art. These devices provide an interfering member in the beam. U.S. Pat. No. 4,463,266 to Brahme describes a collimator which uses wedge shaped slabs mounted on an arcuate surface which moves into the beam so as to define the beam. This device is complicated and expensive to build because of the precision of the fit of the wedges relative to each other. Other prior art includes camera or iris type lenses which uniformly change the diameter beam and thus are not suitable where the beam is to have an irregular cross-section. One prior art example is U.S. Pat. No. 4,534,052 to Milcamps. None of this prior art provides a means for rapidly and simply adjusting the beam cross-section non-uniformly.